磁控溅射制备的陶瓷涂层SiO2/PP/AlF3隔膜对电池性能影响

Effect of ceramic coating SiO2/PP/AlF3 separator prepared by magnetron sputtering on battery performance

本工作利用磁控溅射技术对PP隔膜两侧分别物理沉积了厚度为200 nm的SiO2和AlF3陶瓷颗粒层,成功制备了SiO2/PP/AlF3功能隔膜,有效避免了传统涂覆法带来的厚度增加和孔隙率降低的缺陷。一方面,SiO2和AlF3陶瓷颗粒均具有优异的力学性能和化学稳定性,能够有效提高聚烯烃(PP)隔膜的耐热性;另一方面,SiO2和AlF3都是极性化合物,能够协同提高隔膜对电解液的亲和性,提高了锂离子的电导率,降低电池内阻。此外,AlF3的强路易斯酸性和低表面能有效抑制电解液的分解和锂枝晶的生长,提高锂离子电池的电化学性能和安全使用性能。通过扫描电子显微镜(SEM)、X射线能谱分析技术(EDS)、差示扫描热量仪(DSC)、X射线光电子能谱仪(XPS)、孔隙率、电解液亲和率以及电化学性能测试对改性隔膜进行表征。结果表明,磁控溅射技术对改性隔膜的厚度和孔隙率影响很小;采用SiO2/PP/AlF3隔膜的锂离子电池,在0.2 C下的初始放电比容量达到164.98 mA·h/g,50次循环后的比容量为154.87 mA·h/g,循环衰减率仅为0.12%;在5.0 C高电流密度下SiO2/PP/AlF3隔膜电池仍有102.07 mA·h/g放电比容量,循环性能、倍率性能明显优于传统的PP隔膜电池。SiO2/PP/AlF3功能隔膜的应用对高性能锂离子电池的研发具有积极意义。

Magnetron sputtering technology was used to deposit SiO2 and AlF3 ceramic particle layers with a thickness of 200 nm on both sides of a polypropylene(PP)separator.The preparation of a SiO2/PP/AlF3 functional separator prevents the pitfalls of increased thickness and decreased porosity caused by traditional coating methods.In general,SiO2 and AlF3 ceramic particles have excellent mechanical properties and chemical stability,properties which can improve the heat resistance of a polyolefin(PP)separator.In addition,the nonpolar SiO2 and AlF3 can synergistically improve the affinity of the separator to the electrolyte,thereby promoting the conductivity of lithium ions and reducing the internal resistance of the battery.In addition,the strong Lewis acidity and low surface energy of AlF3 effectively suppresses the decomposition of the electrolyte and the growth of lithium dendrites,improving the electrochemical performance and safety of lithium-ion batteries.The modified separator was characterized using scanning electron microscopy(SEM),energy-dispersive X-ray spectroscopy(EDS),differential scanning calorimetry(DSC),and X-ray photoelectron spectroscopy(XPS).The porosity,electrolyte affinity,and electrochemical performance were also measured.The results show that magnetron sputtering has little impact on the thickness and porosity of the modified separator.The lithium-ion battery with a SiO2/PP/AlF3 separator has an initial discharge specific capacity of 164.98 mA·h/g at 0.2 C,a specific capacity of 154.87 mA·h/g after 50 cycles,and a cycle decay rate of 0.12%.The battery prepared with a SiO2/PP/AlF3 separator has a discharge specific capacity of 102.07 mA·h/g at a high current density of 5.0 C.Overall,the cycle and rate performance were significantly better than batteries with a traditional PP separator.The application of a SiO2/PP/AlF3 functional separator has the potential to inform the development of high-performance lithium-ion batteries.